Adhesive compositions are used extensively in the wood products industry to make composites such as chipboard, fiberboard, and related composite wood products. Adhesive compositions are also used to make engineered lumber composites. Recent environmental concerns emphasize the need for adhesive compositions that are environmentally friendly. Adhesive compositions frequently used in the wood products industry, however, are not environmentally friendly. Thus, the need exists for adhesive compositions that reduce the need for petroleum feedstock, minimize use of toxic chemicals, and are amenable to the cure conditions and performance requirements for wood products.
In response to the need for environmentally friendly adhesive compositions, there has been renewed interest in using certain soy products to form adhesive compositions. However, there are multiple challenges in developing an adhesive composition from soy products. For example, the adhesive composition when cured to form a binder must have sufficient bond strength. The adhesive composition when cured to form a binder should, for certain applications, be sufficiently resistant to moisture. Another challenge is that the adhesive composition must have sufficient pot life so that it does not cure before being applied to components in the wood product. It is also important that the soy product be capable of production on large scale at economically feasible terms, and that it is amenable to cure conditions used to form the wood product.
Various reports describe efforts at developing an adhesive composition using certain soy products. U.S. Patent Application publication 2008/0021187 describes an adhesive composition containing urea-denatured soy flour. U.S. Pat. No. 7,416,598 describes an adhesive composition containing a protein ingredient and a modifying ingredient. Zhong and coworkers describe an adhesive composition containing certain soy protein material that has been modified. Zhong et al. in J. Appl. Polym. Sci. (2007) 103: 2261-2270. Yet, despite these efforts, the need exists for an environmentally friendly adhesive composition that meets the demands for widespread industrial application in the wood products industry.
The present invention addresses this need, and provides other related advantages.